1. Field of the Invention
The present invention relates to a procedure for igniting a combustion chamber, and also to a turbine engine in which the procedure is implemented.
2. Description of the Related Art
In known manner, in a turbine engine, an annular combustion chamber is fed with air by a high-pressure compressor and with fuel by injectors having heads that extend through orifices in an annular chamber end wall, the injectors being regularly distributed around the axis of the chamber. Igniter means, such as spark plugs are fitted downstream from the injectors in orifices through annular walls of the chamber and leading to the inside of the chamber.
On the ground, prior to injecting fuel into the combustion chamber, a starter is put into operation and it drives the rotor of the high-pressure compressor so as to cause air under pressure to enter into the combustion chamber. As from a given speed, i.e. from some given number of revolutions per minute (rpm) for the rotor of the high-pressure compressor, fuel is injected into the chamber at a constant flow rate while simultaneously exciting the igniter means. The fuel is mixed with the air under pressure that enters into the chamber and it is ignited by sparks generated by the spark plugs.
In order to facilitate ignition, it is known to mount some injectors having a greater flow rate than the other injectors in axial alignment with the spark plugs so as to have greater richness of fuel in the vicinity of the spark plugs, thereby guaranteeing that the chamber will ignite rapidly.
Although that configuration ensures that fuel is reliably ignited in the combustion chamber, it is nevertheless found to be more complicated to implement than a configuration in which all of the injectors are identical, since the higher flow rate injectors require their opening valves to be adjusted in a manner that is different from the other injectors. Furthermore, in order to avoid installing a lower flow rate injector in a location that is supposed to receive a greater flow rate injector, it is necessary to provide keying means, thereby complicating fabrication of the chamber. Costs are also increased since, in terms both of fabrication and of maintenance, it is necessary to have injectors of types that present different characteristics.